1. Field of the Invention
The present invention relates to a spindle device and machining center including the spindle devices, and more particularly relates to a spindle device attached to a spindle head of portal machining center and a machining center including the spindle device.
2. Description of Related Art
As a machining center for carrying out working such as cutting and/or drilling by three-dimensional relative movement between a large workpiece and a tool, there has conventionally been used, for example, a portal machining center for causing a straight reciprocating movement of a table to which a workpiece is attached, and for controlling a spindle having a tool in X-axis, Y-axis and Z-axis directions.
In a portal machining center, a saddle is attached to a cross rail supported by two columns, a spindle head is attached to an end of a ram moving in a Z-axis direction with respect to the saddle, and a spindle is pivotably attached to two support arms of this spindle head via a bracket.
In a spindle of this type, a motor-built-in type in which a motor is housed in the spindle, is used, and there is known a machine tool in which a power line for driving this motor and a signal line for a sensor or the like are wired from a spindle head side, and relay connectors are provided to establish connections therebetween (see Patent Document 1, for example).
Patent Document 1: Japanese Patent Unexamined Publication No. JP-A-2006-129611 (FIG. 1)